Three others were killed.
Chris John, an official with the Ketchikan Volunteer Rescue Squad, said it appeared the Beaver crashed on a steep rocky shoreline, ending up partially submerged and upside down.
"All of us at Princess Cruises are deeply saddened by this tragic news", spokesman Brian O'Connor said.Ten others have been hospitalized in Ketchikan, one in critical condition.
The passengers were from the cruise ship Royal Princess and were on sightseeing flights, one of which was operated by flightseeing company Taquan Air. Not clear yet what caused the planes to crash.
Cindy Cicchetti tells The Associated Press that the ship captain announced that two planes were in an accident Monday and said the conditions of the passengers wasn't immediately known. The planes collided mid-air about 1 p.m. about eight nautical miles from Ketchikan, Alaska, at the southeastern end of the state.
Three of the four victims are said to be American.
"We'll also have two people from our Transportation Disaster Assistance Team who will be supporting the Family Assistance Operation", she adds.
This otter float plane operated by Taquan Air, filmed Friday, was involved in a midair crash with another sightseeing plane in Alaska.
Ten other people were injured, and have been taken to hospital for treatment.
(AP AAP) A file photo of a de Havilland DHC-2 Beaver, like the one involved in the collision. The Coast Guard has recovered one body from the aircraft.
The National Transportation Safety Board is to launch an investigation and do not that this is developing news with ongoing new details being released. Three patients are listed in serious condition, seven are in fair condition, Chernick said.
The Coast Guard said in an update Tuesday at least four people died.
Multiple tour companies offer rides through the fjords around Ketchikan, in the southeasternmost part of Alaska, many of which include a water landing in a floatplane. One passenger remains unaccounted for, it said.
At the time of this collision, the National Weather Service says there was 16 kilometres of visibility and it was partly cloudy with 14 km/h southeast winds.